Original subtitles

The debris of the merciless battles of World War II

is still strewn across the remote islands of the Pacific.

Below the waves,

ghost fleets and their cargoes

bear silent testimony to the battles above.

All types of aircraft are scattered on the sea floor.

And on land,

the remains of savage and bloody conflicts.

A tangible museum of the weapons of war,

frozen in time,

charting the track of one of the planet's grimmest

and most far-reaching military campaigns.

For the protagonists,

the vast expanses of the Pacific Ocean were the prize.

Today, history tells its own story through these remains of war.

Deep in the jungle of Bougainville Island

lie the remains from an extraordinary wartime mission.

Admiral Yamamoto was the mastermind

behind Japan's military successes throughout the Pacific.

Unknown to the Japanese,

the Americans had learnt of his proposed flight

to Bougainville

from decoding their radio transmissions.

In an amazing feat of airmanship,

his plane was intercepted and shot down.

Only recently rediscovered,

the wreckage lies deep in the jungle interior of the island.

It marked the first time in known history

that the American military specifically targeted

an individual commander for elimination.

One of only two political assassinations of World War II,

his death had changed the course of the war.

The tide of war was starting to turn

in favour of the Americans and their allies.

The Japanese had been turned back just a stone's throw

from Port Moresby in New Guinea,

from where they had planned to launch their attack

on Australia.

And with Japanese troops eventually and conclusively

driven off Guadalcanal in the Solomon Islands,

the Americans could start planning their own advance

north through the Pacific.

And their first target was the town of Rabaul in New Guinea.

For the Americans, it was essential

that the huge military base at Rabaul be neutralised.

After their defeat on Guadalcanal,

the Japanese had been expecting a land-based assault

and had been preparing to counter this.

What actually occurred was something very different.

The first step on the road to Rabaul

would be capturing the Japanese-held airfields

at Cape Gloucester and Talasea on New Britain Island.

Marines landed at Arawe

on the southwestern side of the island,

some 250 miles away from Rabaul.

But the terrain of New Britain was, to say the least, hostile.

The dense tropical rainforest, jungle, and swamp

that covered most of the island was almost impenetrable.

In the humid jungle,

as much as 16 inches of rain could fall in a day.

Wet uniforms never really dried,

and the men suffered continually from fungal infections,

jungle rot, which quickly developed into open sores.

Mosquito-borne malaria spread rapidly.

Venomous spiders, insects, and snakes compounded the misery.

But the Japanese soldiers were suffering the same conditions,

coupled with near starvation due to lack of rations

as the Marines cut their supply lines.

The relentless progress of the American Green Marine Machine

slowly drove the Japanese back towards Rabaul.

The tide of war had now changed,

and instead of being a forward assault base,

Rabaul was now most definitely under siege.

In the earlier stages of the war,

instead of relying on submarines for sea siege-breaking supplies,

Rabaul had actually been the base

from which marauding Japanese submarines were provisioned.

From a network of shafts and tunnels

carved out by slave labour,

supplies and torpedoes were loaded into submarines

that moored alongside a long-since destroyed jetty.

Today, only the tunnels remain.

The ocean below drops away to over 330 feet.

If an air raid warning sounded,

the submarine would simply submerge down the reef wall

until danger passed.

And in the warm, clear coral shallows,

close to the submarine base,

lies an enigma, a mystery,

a totally intact Japanese ship

that has never been accurately identified.

With her actual name unknown,

she's become known as George's Wreck

after the first salvage diver to discover her.

This 230-foot-long ship

seems to have had an interesting wartime history.

She appears to have started life as a cable-laying vessel

that was then converted to operate as a minesweeper.

The shape of her bow is a clue to her original purpose.

The huge underwater scrapyards of sunken shipping around Rabaul

attracted by salvage hunters in the post-war years,

stripping the ships of any remaining cargoes

and of all non-ferrous metals.

When the first salvage divers discovered the wreck,

her forward hold was crammed with all sorts of cargo,

including Japanese jungle boots, and even toothpaste.

The ammunition locker below the gun

was still filled with live ammunition.

The ship's safe was still intact on the bridge,

and the galley full of cutlery and crockery,

much of it stolen from the Catholic mission nearby.

In the rear hold were cases of sake and Japanese beer

and a consignment of shipping mines complete with spikes.

Of all that cargo, today only a few of the mines still remain.

The Japanese used this bay to shelter ships

that were waiting to resupply the submarine base.

So maybe she was just hiding under the cliff to avoid aerial attack.

Whatever her identity,

her mission, and her reasons for being here,

she was definitely in the wrong place at the wrong time.

As the Americans tightened their stranglehold on Rabaul,

the only way for the Japanese to get men and supplies in

was by sea.

But with the Americans and their allies ruling the daytime skies,

the only time to move was by night.

A most unusual sight.

Two tanks lined up in perfect battle formation on the sea floor.

They'd been on a barge,

lying in the shelter of the Duke of York Islands,

waiting for dusk to start their run for the harbour.

Coast watchers had seen the barge arrive

and tipped off the American Air Force at Cape Gloucester.

Despite being under heavy camouflage netting,

the barge was a sitting duck for the attack planes

and sank to the shallow reef floor.

The wooden barge itself has long since rotted away,

but its cargo remains.

Two fewer tanks to shore up Rabaul's now crumbling defences.

The Japanese expected the attacks on Rabaul

to come from the land and the sea,

and prepared to counter these.

Extensive tunnel systems were dug around Rabaul Harbour

and in the surrounding forests and islands.

And facilities such as hospitals, barracks, storehouses,

and command centres were installed.

In sweltering heat,

British and Australian prisoners of war,

plus slave labourers from Korea,

were forced to build the massive underground military complexes.

This particular complex

comprises around 1,700 feet of tunnels and cabins

on several levels.

This was a kitchen area.

Food was served up to queuing soldiers through a hatch.

On another level was the infirmary.

The wounded would be lined up on stretchers

while waiting to be operated on.

Other areas also had specific purposes.

This was a workshop.

And this was the weapons store.

The commander had his own separate quarters,

which also doubled as the operations centre.

Of 400 British prisoners of war

shipped from Singapore to Rabaul to carry out this work,

only 18 survived the war.

Secure in their fortifications,

the Japanese sat tight

and waited for the Americans to advance on the town.

But that was not to be.

Where fish now cascade and swirl,

the wreckage of ships strewn across the sea floor

bears witness to the savagery of the Americans' attack on Rabaul

when it eventually came.

Not by land invasion or from the sea, but from the air.

The Americans had learnt lessons from the Guadalcanal campaign

and other opposed and bloody landings.

And they knew that the Japanese had turned Rabaul

into a formidable fortress.

A land invasion,

whether from ships or overland through New Britain,

would have been massively costly in American lives.

So another approach was needed, isolate and neutralise.

In early November 1943, wave after wave

of American Air Force and Navy planes attacked Rabaul.

The strike was a stunning success.

By the end of the attacks,

6 of the 7 Japanese cruisers in the harbour had been damaged,

and 56 ships had been sunk.

Losses among the attacking aircraft were light.

Around 65 shipwrecks today litter the sea floor of Rabaul Harbour.

Some of these have become bright, vibrant oasis of life,

while many others are partly or fully buried

under layers of volcanic ash.

The day after the raid,

the surviving Japanese warships departed for Truk Lagoon,

effectively ending Japan's naval presence in the area.

Isolated and subject to continued bombing raids,

the town was neutralised as an effective military base.

And some 70,000 troops were bottled up there

until the garrison eventually surrendered at the end of the war.

Despite the Americans' vast air superiority,

some Japanese planes had managed to take to the air.

Though few actually survived the battle.

Fast, incredibly manoeuvrable, and with a range of over 1,000 miles,

the Japanese Mitsubishi Zero

was one of the most successful fighter planes of World War II.

A very different crashed plane.

This biplane, the Mitsubishi F1M, nicknamed the Pete,

was another workhorse of the Imperial Japanese Navy.

It was originally built

as a catapult-launched reconnaissance floatplane.

But the Pete took on a wide variety of roles,

including convoy escort,

bomber, anti-submarine patrol,

rescue, and general transport duties.

Its downfall was that it was slow,

and so no match for Allied airpower.

In a jungle-shrouded cave 1,600 feet from the sea

are the rotting remains of 5 Japanese wartime barges.

Barges were of massive value to the Japanese forces.

With Allied air power preventing major shipping movements,

many supplies were brought in by submarines,

which would rendezvous with barges under the cover of night

to offload cargoes.

But the barges were defenceless by day against aerial attacks.

So each morning, these cranes lifted them out of the water

and they were hauled along rail tracks

to their daytime cave hideaways,

often several hundred feet inland.

The loss of Rabaul as an effective naval base

was a critical blow to the Imperial Japanese plans

for domination of the Pacific.

From now on,

rather than being on the offensive,

the tide of war was definitely flowing against them.

From Rabaul,

the remainder of the Japanese fleet

had retreated to the remote Truk Lagoon.

Between the two World Wars, under a veil of secrecy,

Japan had built a formidable naval base there.

Its position in the very heart of the South Pacific Ocean

meant that ships and planes based there

could interfere with American supply lines

and inflict substantial losses to shipping.

It had to be neutralised.

The lagoon bristled with defences.

The small island of Eten had been enlarged by land reclamation

to create a huge fighter base.

On the adjacent island of Dublon,

the Japanese had built a giant seaplane facility.

Airfields built on outlying islands

provided an additional protective shield of fighter planes.

In total, the garrison consisted of over 40,000 men.

The Japanese thought Truk was invincible,

but the Americans had other ideas.

So Operation Hailstone was conceived,

masterminded by Admiral Chester Nimitz.

A massive carrier-based airstrike

along the lines of the raid on Rabaul.

The American payback for the attack on Pearl Harbour.

With Japan itself now firmly in their sights,

the American high command knew

they could not continue to squander lives and material

on land assaults on the islands that lay in their path.

Bitter experience had already taught them that.

In November 1943, the American assault on Betio,

a tiny islet on the Tarawa Atoll,

just 3 miles long and under half a mile wide,

had cost over 3,000 Marines dead and injured in just 3 days.

American bodies were lined up on the beaches.

Others drifted in the surf.

Of the 4,700 Japanese and Korean defenders,

just 17 survived.

The message was clear.

The Japanese intended to fight to the last man

to defend each and every island that lay in the Americans' path.

The price paid in dead and wounded

was a major factor

in the decision to plan Operation Hailstone very differently.

Over 2 days in February 1944,

American aircraft sunk around 40 Japanese ships

and destroyed hundreds of warplanes.

The Kensho Maru is typical of many vessels

that were sunk in the lagoon,

ships that were caught in a firestorm of bombs and bullets,

sinking on the spot.

Entering the bridge, most of the essentials are still there.

The telegraph signalled to the engineer

the revs at which to run his engines

and whether to engage forward

or reverse drive.

The ship's radio equipment still stands upright

in the communications centre.

On the next level down from the bridge

is the officers' mess.

The huge stove in the ship's galley

is where the cook would prepare all meals

for officers and ratings alike.

A large wok still rests on the top.

Breakfast would just have been served when the attack came.

A catwalk leads across the upper level of the engine room,

a vast space dropping 3 levels below, down to the very bilges.

When the ship was running,

this would have been a loud, sweaty,

and hot environment to work in.

Steps drop down to the engine room floor.

This is one of the shallower wrecks,

but here it's still over 100 feet below the sea surface.

80 years on,

a light bulb looks as if all it needs is a flick of a switch.

Control panels and levers, some on and some off,

are caught forever in that moment of acceptance

when it became clear

that no matter how hard the crew tried to save her,

the ship was sinking, and sinking fast.

You can picture the engine room crew panicking

and scrambling up the ladders to avoid being entombed here forever.

Looking at the harbour today,

it's hard to believe that Truk was the Japanese Empire's

largest naval base in the South Pacific.

At times, there would be over 100 ships of all descriptions

sheltering in the lagoon,

from giant battleships and aircraft carriers

to small cargo ships and freighters.

There were plenty of supplies on the islands

for crews that had been at sea for months,

and there was plenty of alcohol too.

This cargo of beer bottles

in the hold of the Rio de Janeiro Maru

was being unloaded when the attack struck.

Ships' holds contain construction equipment

intended to fortify the atoll's defences.

Bulldozers for excavations and creating obstacles to invaders.

Road rollers for flattening runways.

Trucks for transporting building materials.

Tractors for heavy haulage.

The Nippo Maru had such a varied cargo of war materials

that she's a time capsule in miniature

of the day-to-day activities of the Japanese military on Truk.

The ship's steel bridge is still intact,

with an engine room telegraph and a helm for steering.

The wooden spokes of the ship's wheel have long since rotted away,

leaving just the metal rim hanging on its support.

She was basically a single-purpose ship.

Her official wartime designation was a water supply vessel.

None of the outer islands of the atoll

had any natural water supply, being merely coral and sand.

So with large numbers of troops manning these

against the predicted invasion,

it was essential that they all received regular water supplies.

Today, schools of fish

swirl around her deck and her structures.

Deck space was utilised to transport a tank.

It was being sent to the outer islands

to counter the expected amphibious assault.

Perhaps the quirkiest items of deck cargo

are the 3 anti-tank howitzers.

Of American manufacture,

they were probably captured from American troops in the Philippines

and were now bound for the outer islands

to be used against their makers.

Swimming weightless along the ship's companionways,

it's hard to imagine the panic moments before she sank.

Realising she could not be saved,

the captain gave the orders to abandon ship,

and sailors grabbed their few belongings

before scrambling over the rails and taking to the lifeboats.

In reality,

the Americans had absolutely no idea what they would find at Truk.

The only reconnaissance flight that they had managed to make

was in early February 1944,

when two Marine Liberators flew the 1,700-mile round trip

from Bougainville to photograph the base.

Visibility had been hampered by low clouds.

But they had spotted many warships and cargo vessels

anchored close to Eten Island.

In total secrecy,

5 fleet carriers plus 4 light carriers

steamed towards Truk.

They were supported by a screen of battleships, cruisers,

destroyers, and submarines.

The American attack fleet

managed to get as close as 90 miles from the islands

before the planes were readied for action.

When the attack came,

it took the Japanese by total surprise.

Just like the Americans at Pearl Harbour,

they never dreamt that an aerial attack on the base

was even possible.

Before dawn on the 17th of February, 1944,

strike groups of Hellcat fighters swept in low.

Japanese radar technology

was still in the early stages of development

and unable to detect the approaching American fleet.

Nor was it able to detect low-flying aircraft.

The Americans' first target at Truk

was to destroy the airfields and as many aircraft as possible.

More than 500 carrier-based planes swept in on the lagoon in relays.

For the first hour of the onslaught,

the skies over the lagoon saw hundreds of aircraft

involved in one of the biggest and most intense dogfights

of World War II.

The Japanese scrambled to get as many aircraft in the air

as they could to repel the attack.

This wasn't easy,

as most of the pilots were still ashore on the main island.

And not at their bases.

Desperate to at least get some planes up

so they were not hit on the ground,

soldiers pushed traumatised ground crew at bayonet point

into aircraft and ordered them to take off.

A number of Japanese planes managed to get off the ground,

but most were immediately shot down by American fighters.

With air superiority established,

American dive bombers and torpedo bombers

spent the rest of that day and all of the next

sinking all the large ships trapped in the lagoon.

The ships at anchor were effectively sitting ducks.

One such ship, the San Francisco Maru,

was an old freighter

that had been laid up before the war

and used as a floating breakwater.

With the addition of a bow gun,

she was brought back into service

as the Japanese war machine needed anything that could carry cargo.

Built in 1919,

she was a big ship for her time.

Now, over 100 years on,

she sits perfectly upright

with her keel resting on the seafloor

at a depth of 200 feet.

She's known as the Million Dollar Wreck

as she was fully laden with a hugely valuable cargo.

The Americans really hit the jackpot when they sank her.

Her forward hold used to be crammed full of landmines

to be spread along the beaches,

but over the years,

most of these have been removed by the trukees

to create bombs for dynamite fishing.

Other holds contain various cargo.

Tanker trucks that would have been used to refuel aircraft.

Vehicles that would have transported

war materials around the islands.

Even her decks were loaded with cargo

awaiting craning onto the quayside.

Anticipating a seaborne invasion by American troops,

these 3-man Mitsubishi light tanks

were designed to wreak carnage among attacking infantry.

In fact, the ship's whole cargo

had been intended to bolster the lagoon's shore-based defences

against that American attack.

An attack which never came,

at least not in the way that it was expected.

The tanks still rest as they ended up

when the ship hit the sea floor,

the force of that impact throwing one on top of the other.

In the dim half-light at this depth,

the sun barely penetrates,

and even over 80 years on from her sinking,

unlike shallower wrecks,

there's minimal growth on the ship.

This plane, known as a Betty bomber,

almost made it,

but it was hit on takeoff

and crashed just off the end of Eten's runway,

hitting the water so hard that its engines broke off on impact.

They carried a large fuel load

to enable them to fly long distances,

but their unprotected fuel tanks proved their greatest undoing.

The Americans nicknamed these planes

Flying Cigarette Lighters

because whenever they were hit, they went up in flames.

Armour had been sacrificed in return for lighter weight

and increased range,

but they were extremely vulnerable,

offering minimal protection for the 8-man crew.

It was on board a similar plane

that Admiral Yamamoto had met his fate in Bougainville

the previous year.

The huge variety of ships and cargoes

gives us a snapshot frozen in time of Truk's story.

One of the lagoon's shallower wrecks is the Fujikawa Maru.

With her superstructure almost breaking the surface,

she's been richly colonised by both soft and hard corals.

She'd been built shortly before the war

as a combined passenger and cargo ship,

plodding the sea lanes of the Pacific.

She'd never been designed as a ship of war,

but in 1940, she was requisitioned by the Japanese Navy as just that.

The armaments on the Fujikawa Maru were basic and ancient,

a no-match for the attacking American squadrons.

On her bow and stern were fitted 6-inch guns

that had actually been captured by the Japanese

during the Russo-Japanese War at the turn of the century.

A plate on the breech of one of these guns

says it was made in 1899 by a British manufacturer,

so that by the time it was fitted to the Fujikawa,

the gun was already 40 years old.

The Fujikawa Maru was being used as an aircraft transport ship,

for Zero fighter planes

to deploy them to the outposts of the Japanese conquest

when she was attacked at Truk.

In one of her holds,

there are still around 20 part-assembled Zeros

stacked on top of each other.

They were in the midst of being unloaded when the attack began.

The parts would be winched ashore and then in huge workshops,

the planes would be assembled

either for use in the defence of Truk

or for onward dispatch to carriers

or air bases around the Pacific.

Many other plane parts,

belly tanks, propeller blades,

wheels, and struts are in the forward holds,

along with large artillery shells.

Her holds were crammed with oil drums

and other supplies to feed the Japanese war machine.

Already, her war service had seen the ship involved in campaigns

as wide-ranging as the Aleutian Islands in the Arctic Circle,

down to Rabaul at the very southern tip

of the Japanese sphere of influence.

Twice before, she had been attacked and repaired.

For the Fujikawa Maru, it was third time unlucky.

This plane was headed to Truk

with several high-ranking Japanese officers on board,

believed to include Vice Admiral Hara,

commander of the 4th Fleet and 4th Base Force.

Mid-flight, she was ambushed by American fighters,

who killed many of those on board, including the co-pilot.

Injured and flying single-handed,

the pilot lost the Americans

and managed to limp back to Truk Lagoon.

Although a seaplane and designed to land on water,

she'd been so badly damaged in the attack

that she broke up on impact

and now lies in 3 pieces on the sea floor.

It's a Kawanishi Type 2 flying boat,

nicknamed the Emily by the Americans.

The Emily was the workhorse of the Imperial Air Force.

Swimming along the wing gives you an idea of the size of the plane.

Some say the Emily was the best all-round plane of World War II.

Carrying a 16-man crew, it bristled with so many guns

it was also known as the Flying Porcupine.

As the only Japanese aircraft with self-sealing fuel tanks,

internal fire extinguishers, and an armoured cockpit,

it was extremely difficult to shoot down.

This formidable opponent

could cruise at over 200 miles an hour for 4,500 miles,

a range greater than even the Americans' B-29 Superfortress.

Expecting a seaborne land invasion,

the Japanese constructed their buildings to last.

So much so that even 80 years on,

an island family have moved in and it has become their home.

This colossal bunker looks as if even now

it could withstand a serious bombing raid.

The busy seaplane base needed a constant supply of fuel.

While some of these aviation fuel storage tanks survived intact,

others took direct hits

and the melting metal was distorted into fantastic shapes.

For the islanders,

these relics of war

are just an unremarkable feature of their day-to-day life.

The Aikoku Maru was a very beautiful ship

and one of the largest in the lagoon.

Designed as a passenger-cargo vessel,

she was planned to be used on the Japan-to-Africa run,

but in fact never entered this service

because she had already been acquired by the Japanese Navy

and converted for use as an armed merchant raider.

Aikoku had only that morning arrived in Truk

carrying 1,000 troops

to bolster the island's defences when the Americans attacked.

Like many other ships,

she was to meet her fate here in Truk Lagoon.

Attacked by a squadron of Avengers from the USS Intrepid,

she fought back.

The Japanese anti-aircraft gunners were extremely accurate.

Unable to pull out of the attack,

having been fatally hit,

a blazing American plane

crashed into the forward hold of the Aikoku,

where all the ammunition was stored.

The force of the explosion was instant and terrifying,

producing a nuclear-like mushroom cloud.

Pieces of the ship were hurled in the air

and scattered for miles around.

When the cloud cleared,

the ship had already disappeared below the sea.

There were only 2 survivors.

Today, the huge stern gun of the Aikoku

points impotently towards the surface.

Even this powerful naval gun

had been insufficient to save her from her fate.

Truk was a surgically successful masterstroke,

reducing much of the island's defences to rubble.

The statistics were staggering.

In Operation Hailstone,

a total of 40 Japanese ships and 275 Japanese aircraft

were destroyed.

Along with tens of thousands of tons of fuel and supplies,

at a cost of just 25 American planes.

Of those planes that were hit by Japanese anti-aircraft fire,

many managed to limp back to their carriers.

With the island totally neutralised

as an effective military base,

the American forces simply bypassed it

in their steamroller advance through the Pacific.

With each island taken, they inched even closer to Japan.

Growing superiority at sea and in the air

gave the United States ever more advantages.

Nonetheless, wherever American forces met the Japanese,

the defenders fought long and hard before they were defeated.

And nowhere more so than on the tiny island of Peleliu,

among the rock islands of Palau.

In the next episode,

destruction of the Japanese fleet in Palau.

A 3-month battle to the death on a tiny island.

The final surrender of the last Japanese soldiers

and how not to deal with the unwanted materials of war.

Subtitles: RTÉ 2026